Digital devices have become indispensable and important elements in people's lives and during the production. Display devices, taken as video signal output terminals of the digital devices, are configured to directly transmit information to operators and belong to necessary devices. With the development of science and technology, the display device is not limited to receive signals for display but also has the function of controlling command input. A touch display device can be used to directly enter commands through a screen and even can replace an auxiliary device for input, e.g., a keyboard.
A capacitive in-cell touch panel is obtained by directly and additionally arranging touch scanning lines and touch sensing lines on a thin-film transistor (TFT) array substrate. That is to say, two layers of indium tin oxide (ITO) strip electrodes which intersect each other in different planes are formed on a surface of the TFT array substrate and respectively taken as touch driving lines and touch sensing lines of a touch screen, and a sensing capacitor is formed at the intersection of two ITO electrodes in different planes. The working process of the capacitive in-cell touch panel is as follows: in the process of loading touch driving signals to the ITO electrodes taken as the touch driving lines, voltage signals coupled by the touch sensing lines through the sensing capacitors are detected; in the process, when the touch screen is touched by the human body, coupling capacitors are formed between the human body and touch driving electrodes as well as touch sensing electrodes in the touch screen; the coupling capacitors act on the sensing capacitors, so that the capacitance of the sensing capacitors can be changed, and hence the voltage signals coupled out by the touch sensing lines can vary; and thus, the position of the touch point can be determined according to the variation of the voltage signals.